1. Field of the Invention
The present invention relates to disk drives. More particularly, the present invention relates to disk drives that include a vertically adjustable ramp load.
2. Description of the Prior Art
Ramp-loading disk drives utilize a ramp to transition a flying head off-of and back-onto a flying area above the surface of the rotating disk. The ramp typically interacts with a lift tab that supports the flying head. The disk is spun-up while the lift tab is on the ramp and the head is not in contact with the disk. Once the disk is rotating at a specified speed, the lift tab is moved down the ramp such that an air bearing is developed between the head and the disk. The head may then move free of the ramp. Before the disk is spun-down, the lift tab is moved onto the ramp such that the head is moved away from the disk.
One method of increasing the storage capacities of disk drives is to store data more densely on each disk. One of the consequences of storing data more densely on a disk, however, is that the heads must be correspondingly decreased in size and must fly closer to the recording surface of the disk. Another method of increasing the storage capacity is to manufacture disk drives with a greater number of stacked platters (individual disks). The later method has led to relatively tall disk stacks including, for example, four or more individual disks, each of which has two recording surfaces. However, it has proven difficult to precisely align each of the ramps relative to the respective recording surfaces of each disk in a tall disk stack. Indeed, the manufacturing tolerances of the disk stack, when summed over each disk of the stack, are such that it becomes difficult to correctly position the ramps so that each of the ramps is precisely positioned at the correct height over the recording surface of its respective disk.
What are needed are ramps that minimize the effects of manufacturing tolerances of the disks of a disk stack. What are needed, therefore, are ramps that minimize the alignment offset between the ramps and the disks.
Accordingly, this invention may be regarded as a disk drive, comprising a disk drive base; a disk stack, the disk stack comprising a first disk including a first recording surface and a second recording surface; a spindle motor for rotating the disk stack about a spindle motor rotation axis, the spindle motor being attached to the disk drive base; a head stack assembly including a first lift tab and a second lift tab; a ramp load for engaging the first and second lift tabs, the ramp load comprising a shaft coupled to the disk drive base, the shaft defining a shaft axis that is parallel to the spindle motor rotation axis; a first ramp defining a first lift tab engaging surface for engaging the first lift tab and a first facing surface configured to face the first recording surface of the first disk at a first distance, and a second ramp defining a second lift tab engaging surface for engaging the second lift tab and a second facing surface configured to face the second recording surface of the first disk at a second distance, the first and second ramps being configured to be selectively slid in a direction that is parallel to the shaft to a desired position wherein a difference between the first distance and the second distance is minimized and to be locked onto the shaft at the desired position.
The disk drive may further comprise a ramp assembly configured to selectively slide over and lock onto the shaft and wherein the first and second ramps are unitarily formed with the ramp assembly. The first ramp may be integral and unitarily formed with the second ramp to define a ramp pair. The disk drive may include a plurality of ramp pairs, each ramp pair of the plurality of ramp pairs being configured to be selectively and independently slid and locked onto the shaft.
The ramp assembly and the shaft may be shaped so as to enable an interference fit of the ramp assembly to the shaft. Alternatively, the disk drive may further include a ramp assembly fastener that is adapted to fasten and lock the ramp assembly onto the shaft. The ramp assembly may include a shaft-contacting surface that defines a through bore dimensioned to fit over the shaft. The shaft may a unitary extension of the disk drive base. The shaft and the disk drive base may be formed of the same material. The first ramp and the second ramp may include a plastic material. The first and second ramps may include molded plastic and the shaft may include a metal.
The foregoing and other features of the invention are described in detail below and set forth in the appended claims.